I have the opposite problem
. I have a dual boot XP/SuSE 9.1(which is really awesome btw) and in SuSE the fan only starts up when starting YaST or if my laptop is on for quite a while, but i feel that my laptop warms up more than in windows. In XP, the fan runs almost all the time, but he keeps the temperature stable during the whole time, in suse he let's it warm up and when necessary, he activates...
But I can understand your problem, especially with an AMD processor. I have about the same one myself on my laptop, Athlon XP-M 2600+ and it gives a better performance than an intel processor, but warms up a lot more and faster.
Really hope someone can find what the cause is and how to solve it